Regensburg 2004 – wissenschaftliches Programm

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SYPF: Physics of Foams

SYPF 2: Foams II

SYPF 2.2: Vortrag

Mittwoch, 10. März 2004, 14:50–15:10, H16

Effect of colloidal charges on the thickness of foam films — •Regine v. Klitzing, Branko Kolaric, and Tatjana Mauser — Stranski-Laboratorium, TU Berlin, Str. d. 17. Juni 112, 10623 Berlin

Polymers can be used as stabilizers of foams. To use polymers in an efficient way in surfactant systems, it is necessary to control and to manipulate the building blocks, i.e. the single free-standing surfactant films of a foam. In our experiments the film thickness is controlled on a mesoscopic length scale (5-100 nm) by varying the outer pressure in a thin film pressure balance. The sum of interactions (DLVO, steric, structural forces) between the film surfaces is determined quantitatively by the disjoining pressure. The addition of polyelectrolytes affects the (de)stability of the film due to complexation between polymer and surfactant at the film surfaces. In dependence on the charge combination of the surfactant and polyelectrolyte either a Newton Black Film (NBF, stabilized by steric repulsion) or a Common Black Film (CBF, stabilized by electrostatic repulsion) occurs at high outer pressure. The influence of polyelectrolytes on the film stability is compared to the effect of hard colloids.